6 Observations and Experiments, made 



thermometer, that morning, till half past eight o'clock) 

 I was assured by other observers, that, about two 

 hours before sun-rise, it was considerably below zero! 

 This surely might have rivalled the '■'■ frigus penetra- 

 hile adiirens'''' of the Roman poet, supposed capable 

 of piercing through the bones to the very marrow. 

 Unaware, however, were the ancients of that admira- 

 ble provision in the human frame, which constantly 

 preserves the internal parts of the same equal tem- 

 perature, in the depth of winter as in the midst of 

 summer ; within the polar circle as under the equator. 



On examining the liquors upon the garden wall, I 

 found, to my astonishment, all of them (except the 

 alcohol and vitriolic aether) perfectly congealed : the 

 first time I had ever seen wine, brandy, and spiritous 

 liquors in a solid form 1 



Experiment 4. Being desirous to try the effects of 

 a high degree of artificial cold, added to the natural 

 cold that now prevailed, an ounce of quicksilver, in 

 an open phial, was placed in a frigorific mixture, con- 

 sisting of snow, with vitriolic acid, &c. In the act 

 of solution (during which the greatest degree of cold 

 is generated) the thermometer was immersed in the 

 frigorific mixture, which, in a few seconds, sunk the 

 quicksilver far below zero, even into the bulb of the 

 thermometer, when the quicksilver, both in the ther- 

 mometer and in the phial, suddenly assumed the ap- 

 pearance of a thin plate of lead, placed on the surface 

 of fluid quicksilver below, which doubtless was a real 

 mark of incipient congelation. But unfortunately, at 



